cfg80211: fix dfs channels remain DFS_AVAILABLE after ch_switch

Depending on the regulatory domain, leaving a DFS channel requires
a new CAC to be performed when returning back to that channel.
If needed, update dfs states after a driver channel switch.
Signed-off-by: Michael Vassernis <michael.vassernis@tandemg.com>
Link: https://lore.kernel.org/r/20190729060024.5660-1-michael.vassernis@tandemg.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -16118,6 +16118,8 @@ void cfg80211_ch_switch_notify(struct net_device *dev,
 	    !WARN_ON(!wdev->current_bss))
 		cfg80211_update_assoc_bss_entry(wdev, chandef->chan);
 
+	cfg80211_sched_dfs_chan_update(rdev);
+
 	nl80211_ch_switch_notify(rdev, dev, chandef, GFP_KERNEL,
 				 NL80211_CMD_CH_SWITCH_NOTIFY, 0);
 }